Methods of making dynamoelectric machinery

ABSTRACT

A dynamoelectric machine including stator and armature structures. The stator includes a yoke and a plurality of pole shoes carried thereby which include slots for receiving compensating coils. Strand-like elements are tightly packed within the slots between the compensating coils and the slot walls and are embedded within a hardened binder material, to support the coils against oscillation. Each pole shoe includes tip and base sections defining a pole face. The tip section comprises a plurality of lamination plates which have aligned apertures defining an opening extending through the tip section remote from the pole face. A connecting bar is disposed within this opening and has fastener elements mounted on each end thereof to clamp the lamination plates together. Threaded bolts are received in the connecting bar to draw the lamination plates toward the base section in uniform fashion. The yoke comprises a plurality of lamination plates which are arranged in mutually abutting relationship. A plurality of attachment flanges are welded across the outer edges of yoke plates to couple the plates together. The shoe base section is detachably secured to the yoke such that shoulder portions of the base section serve to clamp primary current windings in place against the yoke.

[111 3,885,302 [4 1 May 27, 1975 United States Patent [191 Boesel [57]ABSTRACT A dynamoelectric machine including stator and armal METHODS OFMAKING DYNAMOELECTRIC MACHINERY inventor:

[75] Walter Boesel Palos Verdes ture structures. The stator includes ayoke and a plu- Estates Calif. rality of pole shoes carried therebywhich include slots for receiving compensating coils. Strand-likeelements Asslgnee: The Garrett Corporatlon, L05 are tightly packedwithin the slots between the com- Angeles, Calif.

pensating coils and the slot walls and are embedded within a hardenedbinder material, to support the coils against oscillation. Each poleshoe includes tip and base sections defining a pole face. The tipsection comprises a plurality of lamination plates which have alignedapertures defining an opening extending [22] Filed; Sept. 27, 1974 [21]Appl. No.: 509,977

Related US. Application Data [62] Division of Ser. No. 383,174, July 27,1973, Pat. No.

3 859 549 through the tip section remote from the pole face. Aconnecting bar is disposed within this opening and has fastener elementsmounted on each end thereof to clamp the lamination plates together.Threaded bolts are received in the connecting bar to draw the lamination plates toward the base section in uniform fashion. The yokecomprises a plurality of lamination plates which are arranged inmutually abutting relationship. A plurality of attachment flanges arewelded across mmmlm 00 /5 01 t O 5 1 2 3 2m .9 0/OO 2 H0 4 2 w m 1m m l3 W 3 a N6 9 m 5 m n no 9 u C n r U u u& a a S .M Mk U IF U UN 5 55 .l.[.l.

References Cited UNITED STATES PATENTS the outer edges of yoke plates tocouple the plates together. The shoe base section is detachably securedto the yoke such that shoulder portions of the base section serve toclamp primary current windings in place Raby....- against the yoke.

wm m .mo RG 7 5 9 1 4 3,761,754 9/1973 Boesel... 3,797,106 3/1974Costello 6 Claims, 6 Drawing Figures Primary Examiner-Carl E. HallAttorney, Agent, or Firm-Albert J. Miller MAKING DYNAMOELECTRICMACHINERY This is a divisional of application Ser. No. 383,174, filedJuly 27, l973,.now US. Pat. No. 3,859, 549.

BACKGROUND AND OBJECTS OF THE INVENTIONS This invention relates todynamoelectric machines such as electric motors and generators.

In dynamoelectric machines having a commutating armature there is alwayspresent the problem of a cross-magnetizing field in the armature createdby the load current therein. This problem is of little consequence insmaller machines, but when the machine size becomes greater than a fewhorsepower, and when maximum overload and broadest speed range aredesired, it is advantageous to provide the machine with compensatingwindings coupled in series with the armature. This tends to neutralizethe crossmagnetization to the extent possible.

Problems occur in attempting to adapt a dynamoelectric machine toreceive the compensating coils. While it is desirable to provide aneffective orientation of the compensating coils, it is also importantnot to impair overall machine performance or or unduly complicate theassemblage and disassemblage of the machine components.

It has been previously proposed to provide dynamoelectric machines withdetachable pole shoes which contain slots for receiving the compensatingcoils. Exemplary of such a proposal are Rimkus U.S. Pat. No. 2,745,031,issued May 8 1956 and Potter US. Pat. No. 2,679,607 issued May 25, 1954.

In Rimkus, the coil-receiving slots are intended to be open-ended andclosed-sided. One assemblage problem posed by close-sided slots is thedifficulty involved in threading small-stranded conductors axiallytherethrough, an operation akin to attempting to push a rope from theend. In addition, Rimkus proposes that a groove be formed in the poleface for the reception of a cross-bar intended to serve in mounting thepole shoe to the yoke. Such a groove constitutes an interruption in thepole face and might tend to reduce the fluxconducting efficiency of thepole shoe.

The Potter patent proposes the use of a pole shoe having a main polesection and removable teeth which cooperate with the main pole sectiontodefine coilreceiving slots. The teeth are arranged to abut and supportthe coils. Inconveniences may arise in that re- METI-IODS OF moval ofthe excitation windings would require removal of the compensatingwindings, and vice-versa, in an arrangement where one set of mountingbolts functions to both secure the shoe sections together and attach theshoe to the yoke.

One serious problem associated with the presence of coils within poleslots concerns a tendency of the coils to oscillate, or vibrate,relative to the slot walls during machine operation. This behavior,besides being noisy, produces considerable wear on the coils andnecessitates the use of relative thick insulation around the coils. Useof such insulation reduces the number of wires which can be placed ineach slot and thereby places an unreasonable limitation on thecompensating effectof the coil by limiting the number of ampereturns.Attempts have beenmade to eliminate this oscillation, as by inserting anon-magnetic, non-rigid compound between the slot walls and the coil.The effectiveness of this approach has been found to be of onlytemporary duration, however. Moreover, if a compound is used in slotswhich are slightly open at the pole face, parts of the compound couldbecome detached, leaving depressions in the pole face and resulting inthe introduction of loose debris within the machine.

Construction of the yoke portion of a dynamoelectric machine yoke may beconventionally accomplished by brazing together a series of laminatedplates. This arrangement can be disadvantageous in that the brazingalloy typically occupies space which could otherwise be occupied by yetmore plates, the addition of which would cut hysterisis losses andincrease machine efficiency.

It is, therefore, a general object of the invention to provide novelmethods and apparatus for minimizing or obviating problems of the sortpreviously discussed.

It is another general object of the invention to provide novel methodsand apparatus for optimizing the performance of dynamoelectric machines.

It is a particular object of the invention to provide novel methods andapparatus for effectively resisting oscillation of compensating coilswithin dynamoelectric machine slots.

It is another object of the invention to provide a novel dynamoelectricmachine characterized by simplified assemblage and disassemblage.

It is yet another object of the invention to provide a noveldynamoelectric machine which exhibits minimal hysterisis losses andmaximum efficiency.

BRIEF SUMMARY OF THE PREFERRED EMBODIMENTS OF THE INVENTION Inaccomplishing at least some of the foregoing objects, the presentinvention entails a dynamoelectric machine which includes stator andarmature structures, a plurality of primary current windings, and aplurality of pole shoes carried preferably by the stator structure.

In one feature of the preferred embodiment, each pole shoe comprisesbase and tip sections which are detachable secured to each other anddefine slots for the reception of compensating coils. A plurality ofstrandlike elements are disposed within each slot and are tightly packedbetween the compensating coil and wall portions of the slot. A bindermaterial, such as a resin for example, is poured into each strand-filledslot and allowed to harden so as to embed the strand-like elementstherein. In this fashion, the resin-impregnated, strand-like elementsfunction to restrain the compensating coils from oscillating within theslots.

In another feature of the preferred embodiment, the tip section of eachpole shoe comprises a plurality of lamination plates. The plates includealigned apertures which define an opening extending through the tipsection remote from a pole face that is defined by the outer edges ofthe tip plates. A connecting bar is disposed in the opening and hasfasteners mounted on the ends thereof to firmly clamp the tip platestogether. Threaded bolts extend between the base and tip sections andare received within the connecting bar to draw together the base and tipsections. The connect ing bar serves to draw the tip plates toward thebase section in a generally uniform manner thereby preventing theoccurence of relative displacement of the tip plates. The fasteners atthe ends of the connecting bar may comprise anchor brackets which areattached to the stator to assist in mounting the tip section to a yokeportion of the stator.

In another feature of the preferred embodiment, the yoke portion of thestator comprises a plurality of lamination plates which are disposed inmutually abutting relationship. Aligned recesses in the outer peripheryof the yoke plates define a pluraliy of grooves around the yoke. Thesegrooves receive attachment flanges which are welded to the outer edgesof the yoke plates. In this manner, a maximum number of yoke plates perarea may be provided.

The base section of each pole shoe may be detachably secured to the yokeby means of threaded connectors. Shoulder portions of the base sectionmay be utilized to clamp the primary current windings to the yoke whenthe pole shoe is attached to the yoke by the threaded connectors. Withsuch an arrangement, the pole shoe may be removed from the yoke to allowreplacement of the currect windings, without necessitating unduedisburbance of the compensating coils.

THE DRAWINGS Other objects and advantages of the present invention willbecome apparent from the subsequent de- Y tailed description thereof inconnection with the accompanying drawings in which like numeralsdesignate like elements and in which:

FIG. 1 is a digrammatical view of a portion of a dynamoelectric machine,partly in longitudinal section, in accordance with the invention;

FIG. 2 is a cross-sectional view of a portion of a pole shoe and statorstructure taken along the line 22 in Figure 3;

FIG. 3 is a cross-sectional view taken along line 33 in FIG. 2;

FIG. 4 is a perspective view of a connecting bar element according tothe invention;

FIG. 5 is an enlarged cross-sectional view taken along the line 5-5 inFIG. 3, but not necessarily being to relative scale; and

FIG. 6 is a cross-sectional view of a modified form of the machine inwhich supplemental connecting apparatus is to be'employed in accordancewith the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Adynamoelectric machine 8 incorporating preferred forms of the presentinventive features includes a stator field structure 10 enclosing arotor armature structure 12. The armature 12 is journaled for rotationwithin the stator 10 and may be constructed in accordance with knownprinciples.

The stator 10 includes a yoke 14 which carries a plurality of spacedsalient pole shoes 16 disposed adjacent the periphery of the armature12. Magnetic flux which is produced during machine operation isconducted between the stator and armature by the pole shoes 16. A systemof primary electrical windings 15 is mounted on the stator to conductcurrent in the usual manner.

Each pole shoe 16 includes a base section 18 and a tip section 20. Theshoe sections 18 and 20 are relatively separably connectable, and thebase section 18 is separably connectable to the yoke, by means to besubsequently described.

The yoke 14, the shoe base section 18, and the shoe tip section 20 areeach of laminated construction, being respectively defined by aplurality of lamination plates 24, 26, and 28, as may be viewed in FIG.3. The plates 24 forming the yoke are held together by a plurality ofcross-flanges 30. These flanges 30 extend along the outer yoke peripherywithin grooves 32 formed by aligned recesses in the yoke plates 24. Theflanges 30 may be welded to the yoke plates 24 to hold the plates inside-by-side abutting relationship.

The plates 26 forming the base section 18 are clamped together inside-by-side abutting relation by means of a plurality of clamping bolts34, depicted in FIG. 1.

The manner in which the plates 28 of the tip section 20 are mountedconstitutes a significant aspect of the invention and will be discussedsubsequently in detail.

The base section 18 includes a pair of shoulder portions 36. Theseshoulders 36 serve to clamp the windings 15 to the yoke 14 when the basesection is attached to the yoke by bolts 37. Aligned openings 38, 70,and 42 in the cross flanges 30, the yoke 14, and the base section 18receive the bolts 37. The openings 42 are threaded to receive threadedends of the bolts 37. The mounting end 44 of the base section 18 seatswithin a groove 46 of the yoke 14 to maintain the pole shoe in properorientation.

If desired, the windings 15 may be wrapped around spools (not shown),with each spool being inserted onto a shoe base section.

The laminated plates 28 which form the tip section 20 are arranged inmutually abutting, side-by-side relationship. Aligned apertures in theplates 28 define an opening 48 extending through the tip section.Situated within this opening 48 is a connecting bar 50 which has treadedstuds 52 projecting from opposite sides of the shoe tip 20. Fastenerelements, such as washer and nut assemblies 54 for example, are coupledat the ends of the connecting bar to hold the plates 28 tightly togetheras a unit.

The connecting bar 50 includes a plurality of threaded holes 56 whichare arranged to threadedly receive associated bolts 53 for securing theshoe sections 18 and 20 together. The shank and head sections of thesebolts are respectively located within passages 60 and 62 formed in thebase section 18, The threaded terminal ends of the bolts 53 are receivedwithin bores 64 formed in the shoe tip 20.

It should be understood that when the connecting bar 50 is drawn towardthe base section 18 by the bolts 53, it will engage all of the tipplates 28 and draw them toward the base section 18 in a uniform manner.In this fashion, there will be no relative displacement of the tipplates 28.

Moreover, the connecting bar 50 is disposed remote from the pole face70, defined by the outer edges of the plates 26 and 28, to avoiddistorting the generally smooth configuration thereof.

It will be apparent that with the connecting bar 50, together with thefasteners 54, serving as a means for pressing the plates 28 together,the need for rivets or other coupling devices which might increase thesize of the shoe tip will be elimated.

In the event that relatively short pole shoes are employed, the mountingof the pole shoe may be accomplished by bracket assemblies, one of whichbeing depicted in FIG. 6. The bracket assemblies are disposed atopposite ends of the connecting bar 50'. An anchor brack 66 is mountedat each side of the shoe tip 20 and includes an aperture 67 whichreceives a threaded stud 52' of the connecting bar 50'. The nut andwasher assembly 54' holds the anchor bracket 66 tightly against the shoesections 18 and 20. The bracket 66 includes an outwardly extending leg63. A fastener, such as a bolt 71, for example, passes through this legto hold the bracket 66 to the yoke 14, and thus augment the connectionbetween the pole shoe and the yoke and the connection between the shoesections 18 and 20.

The base section 18 includes a wall 76 that defines a cavity withinwhich the tip section is normally situated. The outer most edges of thetip section 20 and the base section 18, when aligned, form the curvedpole face 70. When these shoe sections 18 and 20 are coupled together,wall portions of these sections cooperate to form a plurality of slots80, 82, 84, 86 for the reception of compensating coils. The front andintermediate sides of the slots 82 and 84 are defined by walls 88, 90,92 on the shoe tip 20, while the back sides of these slots 82 and 84 aredefined by the cavity-defining wall 76 of the shoe base 18.

The slots 80 and 86 each have a back side, one intermediate side, and afront side portion formed by the cavity-defining wall 76 of the base 18(FIG. 2). A wall 100 of the shoe tip 20 cooperates with the wall 76 toform the other intermediate side and the remainder of the front side ofeach slot 80 and 86. A small gap 102 is created at the front of slots 80and 86 between the walls 76 and 100. This gap 102 may be on the order ofone-sixteenth or one-thirty-second of an inch wide, for example.

As will be apparent, with the shoe sections 18 and 20 in a detachedcondition, the slots 80, 82,-84,86 will be open to facilitate convenientinsertion of compensating coils 104, 105, 106, 107 therewithin.Reference may be had to the inventors co-pending application Ser. No.23,756 filed March 23, 1972 for a detailed description of such anarrangement. That co-pending application is incorporated herein byreference.

In order to firmly hold the compensating coils in place within theirreceiving slots, a rigid brace or support structure 110 is interposedbetween the slot walls and the coils. This bracing structure preferablycomprises a cluster of strand-like elements 112 which are embeddedwithin a hardened binder material 114 (FIG.

The strands 112 are fabricated of a rigid non-metallic material such asglass, high temperature nylon, or asbestos fibers, for example. Thebinder material 114 preferably comprises a solventless resin, such aspolyester, epoxy, or silicone. The polyester may be of the type sold byGeneral Electric Co. under Designation No. 702. The silicone may be ofthe type sold by Dow Corning Corp. under Designation No. XR-4-3l26. Whenepoxy is used, it is preferably precoated onto B-stage glass fiberstrands, as are readily commercially available in rope-like form,approximately 3/8% in diameter, each strand being precoated andsemi-cured with epoxy. These resins are typically capable of becomingbonded to the strands as well as the coil and the laminations formingthe walls of the receiving slots.

With the compensating coils 104-107 positioned within their respectiveslots 80, 82, 84, 86 prior to tightening of the bolts 58, the recessesbetween the coils and slot walls may be filled with a cluster of strands112. The clusters may be braided or twisted into rope-like members, orbound into bundles prior to insertion. The bolts 58 may be thentightened to tightly pack the strands between the slot walls andcompensating coils. Strands may be added or removed as is necessary toproperly orient theshoe sections in establishing a substantially smoothpole face 70.

Once a condition is established in which the strands 112 are tightlypacked between the compensating coils and the slot walls, and the poleface-defining edges of the shoe sections are appropriately aligned, theshoe may be laid on-end to receive liquidified, i.e., pourable, resin114, such as polyester or silicone, which is poured downwardly into thestrand-containing recesses. By capillary action, the strands 112 conductthe resin downwardly therebetween. During hardening, the resin becomesbonded to the embedded strands, the coil and the laminations of the slotin the pole piece. In this fashion, the strands will be connectedtogether in compacted relation between the compensating coils and slotwalls, and thus capable of supporting these coils substantially againstoscillatory movements relative to the slot walls. Consequently, the coilexterior will not be subjected to appreciable wear and thus will notrequire the provision of thick insulative jacketing.

The strands 112 tend to reinforce the resin 114 to resist fragmentationof the latter, which fragmentation could otherwise result in theformation of depressions in the pole face and the introduction ofunwanted particles into the machinery. In the event that theaforementioned rope-like elements of epoxy-coated glass fiber strandsare employed as the bracing structure, the pouring step is omitted.Rather, after these members have been inserted within the slots, theyare heated so as to cause the epoxy to liquify. Subsequent curing of theassembly causes the epoxy to become bonded to the coil, the laminationwalls, and the strands.

Although a preferred form of the pole shoe has been described in whichpairs of inner and outer slots are formed, it should be understood thatany number of slots, configured in any suitable manner to receive acomposition of strands and bonding agent, may be provided in accordancewith the teachings of this invention.

It will be apparent that a pole shoe mounting arrangement has beenprovided in which the windings 15 may be easily replaced, as byloosening the bolts 34, without significantly disrupting thecompensating coils 104-107, since the connection between shoe sections18 and 20 will by maintained.

MACHINE ASSEMBLAGE Yoke Assemblage The yoke 14 is preferably assembledby disposing the plates 24 in tight side-by-side abutting relationship,inserting the attachment flanges 30 within the grooves 32, and weldingthe flanges to the plates. This arrangement avoids the loss of spaceoccuring with known arrangements in which yoke plates are directlywelded together by a filler metal disposed between adjacent plates.

Pole Shoe Intercouplin g With the base and tip pole shoe sections 18 and20 in an individually assembled condition, i.e., with the clamping bolts34 tightened and with the fastener asemblies 54 tightened on theconnecting bar 50, the compensating coils 104, 105, 106, and 107 areinserted into the associated open slots 80, 82, 84, and 86. Thus,

the coils 105 and 106 areslipped into the tip section 20 through theopen back side of the-slots 82 and 84, while the coils 104 and 107areinserted between the separated wall portions 76 and 1.00 of the slots80 and 86.

The bolts 53 may then be inserted through the base 18 and into theconnecting bar 50, and are tightened. Prior to final tightening,rope-like cluster of braided, twisted or bound bundles of strands 112are inserted into the recesses between the compensating coils and theirassociated slot walls. When thebolts 53 are finally tightened, thestrands become packed tightly together. In the event that there are toomany or too few strands 112 disposed within a slot, rendering itdifficult to align the outer edges of the shoe sections, the bolts 53may be backed off slightly to permit removal or insertion of anappropriate number of strands.

It is noted that as the bolts 53 are tightened, the connecting bar 50distributes the forces of the bolts 53 to all of the tip plates 28.Thus, the plates 28 are uniformly urged toward the base 18 without theoccurrence of relative displacement therebetween and a resulting steppedformation in the tip section as might occur in the absence of this bar.The provision of plateclamping fasteners 54 on the connecting bareliminates the need for separate bolt or rivet elements which couldincrease the size of the pole shoe. Also, by disposing the opening 48remote from the pole face, no gaps or interruptions will be formedtherein to accomodate the bar.

The bolts 53 are tightened such that the strands 112 are tightly packedbetween the compensating coils and the slot walls, and the outer edgesof the shoe section are aligned to form a generally smooth pole face 70.With the shoe being laid on-end such that the openended slots extendvertically, resin 114, in a generally liquid state, is poured into eachslot. The resin is conducted downwardly by capillary action along thestrands until it fills the spaces around, and embeds, the strands.Regarding slots 80 and 86 which include gaps 102, strands disposedwithin the gaps will be embedded within resin which enters the gaps.Upon hardening, the resin becomes bonded to the strands, the coil, andthe laminations, thereby preventing relative movement between thestrands. There is also an adherence of the resin with the walls of theslots, and the coil, thereby maintaining the resin-impregnated strandswithin the associated slots.

As previously noted, in the event that the aforementioned rope-likeelements of epoxy-coated glass fiber strands are employed as the bracingstructure, the pouring step is omitted. Rather, after these members havebeen inserted within the slots, they are heated so as to cause the epoxyto liquify. A suitable heating operation which may be employed is thewell known vacuum pressure impregnation technique. Subsequent curing ofthe assembly causes the epoxy to become bonded to the coil, thelamination walls, and the strands.

During assemblage of the shoe sections, suitable structure may bedisposed along the pole face to facilitate packing of the strands andpouring of the resin.

' The resin-impregnated strands within the gap serve to reinforce theresin and resist fragmenting of the resin during machine operation. Thisavoids the formation of significant depressions in the pole face and thepresence of unwanted loose particles within themachine.

The pole shoes 16 are then coupled to the yoke by inserting the bolts 37through the attachment flanges 30 and into the openings 42. Beforetightening these bolts 37, the windings 15 are positioned between theyoke and the shoulders 36 of the pole shoe. The shoulders 36 serve toclamp the windings 15 in place when the bolts 37 are tigtened.

If it becomes desirable to replace excitation windings, it is merelynecessary to loosen the bolts 37, which may be accomplished withoutdisturbing the compensating windings.

It is noted that if pole shoes of relatively short length are employed,it is advantageous to utilize the anchor bolts 66 to secure the poleshoes to the yoke.

Although the invention has been described in connection with a preferredembodiment thereof, it will be appreciated by those skilled in the artthat additions, modifications, substitutions and deletions notspecifically described may be made without departing from the spirit andscope of the invention as defined the appended claims.

For example, as an alternative to the use of resinimpregnated twistedstrands, rigid resin-impregnated bars having a wedge-shapedcross-section may be used to fill the void between the coil and slotwalls in order to prevent coil oscillations.

What is claimed is:

l. A method of assembling a dynamoelectric machine comprising the stepsof:

adjacently disposing together a plurality of yoke plates;

orienting said yoke plates such that grooves along the outer peripheriesthereof are aligned to form a plurality of grooves;

inserting attachment flanges into said grooves and bonding saidattachment flanges to said yoke plates;

assembling a plurality of pole shoes, each pole shoe being assembled by:

adjacently disposing and securing together a plurality of base plates todefine a base section, adjacently disposing together a plurality of tipplates, orienting said tip plates to define a tip section having acurved pole face, with apertures in said tip plates being aligned todefine at least one opening extending through said tip section remotefrom said pole face, inserting a connector bar through said opening,clamping said tip plates together by clamping elements located at theends of said connector bar,

aligning said base and tip sections such that wall portions of said baseand tip sections define a plurality of slots,

inserting compensator coil windings in said slots,

inserting a cluster of strand-like elements in each of said slotsbetween said wall means and said compensator coil windings,

inserting liquid binder material into said slots and allowing saidbinder material to cure so as to bond said elements together and to saidwall means to define rigid braces supporting said compensator coilwindings against oscillation in said slots, and connecting releasablefastener means between said base section and said connector bar tosecure said tip section to said base section;

- inserting primary current windings around said base sections; and

connecting releasable fastener means between said attachment flanges andsaid base sections to detachably secure said base sections to said yoke,with shoulder portions of each base section supporting said primarycurrent windings;

the arrangement being such that said primary current windings can bereleased from said base section in the absence of removing said tipsection from said base section.

2. A method according to claim 1 including the step I of orienting saidwall means such that at least one of said slots of each pole shoe hasonly one side defined by said base section and at least one other ofsaid slots has at least two sides defined by said base section.

3. A method of assembling a dynamoelectric machine comprising the stepsof:

adjacently disposing together a plurality of yoke plates; orienting saidyoke plates such that grooves along the outer peripheries thereof arealigned to form a plurality of grooves; inserting attachment flangesinto said grooves and bonding said attachment flanges to said yokeplates; assembling a plurality of pole shoes, each pole shoe beingassembled by: adjacently disposing and securing together a plurality ofbase plates to define a base section, adjacently disposing together aplurality of tip plates, orienting said tip plates to define a tipsection having a curved pole face, with apertures in said tip platesbeing aligned to define at least one opening extending through ,said tipsection remote from said pole face, inserting a connector bar throughsaid opening, clamping said tip plates together by clamping elementslocated at the ends of said connector bar, aligning said base and tipsections such that wall portions of said base and tip sections define aplurality of slots, inserting compensator coil windings in said slots,

inserting a cluster of strand-like elements in each of said slotsbetween said wall means and said compensator coil windings,

inserting liquid binder material into said slots and allowing saidbinder material to cure so as to bond said elements together and to saidwall means to define rigid braces supporting said compensator coilwindings against oscillation in said slots, and

connecting releasable fastener means between said connector bar and saidyoke to secure said tip section to said yoke;

inserting primary current windings around said base sections; and

connecting releasable fastener means between said attachment flanges andsaid base sections to detachably secure said base sections to said yoke,with shoulder portions of each base section supporting said primarycurrent windings;

the arrangement being such that said compensator coil windings can bereleased from said slots in the absence of removing said base sectionfrom said yoke.

4. A method according to claim 3 wherein said step of clamping said tipplates together comprises the step of tightening a pair of nutsthreadingly attached at opposite ends of said connector bar.

5. A method according to claim 4 wherein said step of connectingreleasable fastening means between said connector bar and said yokecomprises the step of clamping first ends of a pair of anchor bracketsto opposite ends of said connector bar by means of said nuts, andattaching second ends of said anchor brackets to said yoke by means ofreleasable bolts.

6. A method according to claim 5 including the step of orienting saidwall means such that at least one of said slots of each pole shoe hasonly one side defined by said base section and at least one other ofsaid slots has at least two sidesv defined by said base section.

1. A method of assembling a dynamoelectric machine comprising the stepsof: adjacently disposing together a plurality of yoke plates; orientingsaid yoke plates such that grooves along the outer peripheries thereofare aligned to form a plurality of grooves; inserting attachment flangesinto said grooves and bonding said attachmend flanges to said yokeplates; assembling a plurality of pole shoes, each pole shoe beingassembled by: adjacently disposing and securing together a plurality ofbase plates to define a base section, adjacently disposing together aplurality of tip plates, orienting said tip plates to define a tipsection having a curved pole face, with apertures in said tip platesbeing aligned to define at least one opening extending through said tipsection remote from said pole face, inserting a connector bar throughsaid opening, clamping said tip plates together by clamping elementslocated at the ends of said connector bar, aligning said base and tipsections such that wall portions of said base and tip sections define aplurality of slots, inserting compensator coil windings in said slots,inserting a cluster of strand-like elements in each of said slotsbetween said wall means and said compensator coil windings, insertingliquid binder material into said slots and allowing said binder materialto cure So as to bond said elements together and to said wall means todefine rigid braces supporting said compensator coil windings againstoscillation in said slots, and connecting releasable fastener meansbetween said base section and said connector bar to secure said tipsection to said base section; inserting primary current windings aroundsaid base sections; and connecting releasable fastener means betweensaid attachment flanges and said base sections to detachably secure saidbase sections to said yoke, with shoulder portions of each base sectionsupporting said primary current windings; the arrangement being suchthat said primary current windings can be released from said basesection in the absence of removing said tip section from said basesection.
 2. A method according to claim 1 including the step oforienting said wall means such that at least one of said slots of eachpole shoe has only one side defined by said base section and at leastone other of said slots has at least two sides defined by said basesection.
 3. A method of assembling a dynamoelectric machine comprisingthe steps of: adjacently disposing together a plurality of yoke plates;orienting said yoke plates such that grooves along the outer peripheriesthereof are aligned to form a plurality of grooves; inserting attachmentflanges into said grooves and bonding said attachment flanges to saidyoke plates; assembling a plurality of pole shoes, each pole shoe beingassembled by: adjacently disposing and securing together a plurality ofbase plates to define a base section, adjacently disposing together aplurality of tip plates, orienting said tip plates to define a tipsection having a curved pole face, with apertures in said tip platesbeing aligned to define at least one opening extending through said tipsection remote from said pole face, inserting a connector bar throughsaid opening, clamping said tip plates together by clamping elementslocated at the ends of said connector bar, aligning said base and tipsections such that wall portions of said base and tip sections define aplurality of slots, inserting compensator coil windings in said slots,inserting a cluster of strand-like elements in each of said slotsbetween said wall means and said compensator coil windings, insertingliquid binder material into said slots and allowing said binder materialto cure so as to bond said elements together and to said wall means todefine rigid braces supporting said compensator coil windings againstoscillation in said slots, and connecting releasable fastener meansbetween said connector bar and said yoke to secure said tip section tosaid yoke; inserting primary current windings around said base sections;and connecting releasable fastener means between said attachment flangesand said base sections to detachably secure said base sections to saidyoke, with shoulder portions of each base section supporting saidprimary current windings; the arrangement being such that saidcompensator coil windings can be released from said slots in the absenceof removing said base section from said yoke.
 4. A method according toclaim 3 wherein said step of clamping said tip plates together comprisesthe step of tightening a pair of nuts threadingly attached at oppositeends of said connector bar.
 5. A method according to claim 4 whereinsaid step of connecting releasable fastening means between saidconnector bar and said yoke comprises the step of clamping first ends ofa pair of anchor brackets to opposite ends of said connector bar bymeans of said nuts, and attaching second ends of said anchor brackets tosaid yoke by means of releasable bolts.
 6. A method according to claim 5including the step of orienting said wall means such that at least oneof said slots of each pole shoe has only one side defined by said basesection and at least one other of said slots has at least two sidesdefined by sAid base section.